Process for preparing a jointing composition



p 1950 A. T, B. P. SQUIRES 2,523,731

PROCESS FOR PREPARING A JOINTING courosrrzon Original Filed Aug. 24, 1946 2 Sheets-Sheet 1 mveN R Um Au: T. BR sauna P 1950 A. T. B. P. SQUIRES 2,523,731

PROCESS FOR PREPARING A JOINTING COMPOSITION Original Filed Aug. 24, 1946 2 Sheets-Sheet 2 INVENTOR A KBP. SGANRES gmmm Patented Sept. 26, 1950 PROCESS FOR PREPARING A J GEN TING COMPOSITION Alan Thomas Barrington Parkhurst Squires,

Allenton,

England, assig'nor to Rolls-Royce Limited, Derby, England, a British company Original application August 24, 1946, Serial No.

Divided and this application March 27, 1950, Serial No. 152,066. In Great Britain August 30, 1945 6 Claims.

This application is a divisional of my co-pending United States application Serial No. 692,898, filed August 24, 1946.

This invention concerns production of a new composition of matter.

The invention relates to a composition which is referred to as a jointing substance. The

main application of such a substance is for the purpose of jointing or sealing co-operating surfaces, as, for example, in internal combustion engines. J-ointing substances to which the invention relates, may be prepared to have a low viscosity to permit application of the solution to the surface to be treated, and after the evaporation of solvents which they contain, leave a base medium which has a high degree of tackiness. The properties of low viscosity for application and tackiness after application are very desirable in jointing substances.

According to the invention, a process for the preparation of a jointing substance comprises the addition of sulphur to a fatty oil, heating the mixture at a temperature in excess of 220 C. so as to produce a vulcanized base, and dissolving said base in an organic solvent of a volatile nature to form a solution or dispersion which is in a flowable form to the surface to be treated, evaporation of said solvent producing a base medium of a tacky nature.

Preferably the fatty oil is castor oil or cod liver oil, the temperature to which the mixture is heated is 226 C. and the organic solvent contains toluene, xylene or solvent naptha. Other fatty oils such as linseed, cottonseed or rape oil may be used however.

The use of the jointing substance in internal combustion engines ofiers particular advantages since the jointing medium remains plastic and pliable when exposed for long periods to temperatures up to the melting point of the composition and since moreover the base is resistant to the action of lubricating oils and fuels. Such a jointing substance may be used without the use of a joint washer.

In carrying the invention into practical effect the jointing substance is preparedby adding 20 parts by weight of sublimated sulphur (flowers of sulphur) to 100 parts by weight of castor oil, the mixture so produced being carefully heated, with continuous stirring, to 220 C. at which temperature a reaction takes place accompanied by considerable frothing of the mixture. Whilst this reaction'is in progress the temperature of the mixture is allowed to rise to 226 C. and it is maintained at this temperature with continuous stirring for a period of 2 to 5 minutes. It is pref- (o1. roe-249) erable not to heat the mixture for much longer periods than 5 minutes at this stage.

The mixture is then allowed to cool and throughout this stage of the process it is being continuously stirred until the temperature falls to approximately 200 C. The mixture is then poured into shallow tinned iron trays and allowed to cool to room temperature, the final product being a translucent reddish-brown rubber-like elastic mass.

The vulcanized base thus obtained may be brought into a suitable condition for use as a jointing substance by treating the composition with a suitable organic solvent to convert it to a jelly and then dissolving the jelly in a second organic solvent to form a solution or dispersion which is readily capable of being applied to the joint by means of a brush. For convenience, in describing the above conversions in detail, the composition obtained by the heating of the sulphur and the fatty oil will be referred to as a base, the solution or dispersion applied to the surfaces to be joined together will be referred to as the jointing substance, and the material obtained by evaporation of the organic solvents from the jointing substance will be referred to as the jointin medium. The latter possesses the same properties as the base with the additional property of being very sticky or tacky. Thus; iftwo metal'plates are coated with the substance and the solvent allowed to evaporate, and the plates pressed together and then pulled apart, the medium elongates to numerous threads, showing that it possesses the properties of flowability and adhesion, which it is considered necessary for a jointing medium to possess if it is to function satisfactorily as a sealing medium.

The base, prepared as described, melts at I 195 C. but does not harden when heated for long periods at temperatures below its melting point and it isentirely resistant to the action of lubricating oil and fuel.

The action of various organic solvents towards the base is as follows:

The word insoluble is here used in a broad sense, inasmuch as it covers those instances where the product is only partially or slightly soluble in the solvent in addition to the instances where it is entirely insoluble. The word soluble is used to cover an action which may be the forming of a true molecular solution, a colloidal solution or a colloidal dispersion.

Although the base is capable of being dissolved in toluene, xylene and solvent naphtha these solvents are not sufficiently volatile to ensure rapid drying of the compound when applied to the joint face. However, it has been found that if the base be first mixed with one of these three solvents in suflicient quantity it will form a jelly which is soluble in many of the solvents in which the base alone is insoluble. For example, when 132 parts by weight of the base are added to 100 parts by weight of toluene and the resultant mix boiled under reflux a homogeneous solution is obtained in about 12 hours. Upon coolin the solution sets to a soft jelly. A suitable laboratory apparatus for boiling the basetoluene mixture under reflux is diagrammatically shown in Figure l of the accompanying drawing. The apparatus comprises a doublewall condenser 3, a flask 4 to receive the mixture and a source of heat (such as the gas burner 5) for the flask 4'. A stream of coolant enters and leaves the condenser 3 by conduits 6.

I 'The action on various organic solvents towards the jelly is as follows:

Behaviour Solvent of Jelly Methylated Spirit Insoluble. Trichlorethylene Soluble. Carbon Tetrachlorid Do. Methyl Acetate Do. Ethyl Acetate Do. Butyl Acetate D0. Amyl Acetate Do. Acetone Do. Ben me Do.

EXAMPLE I "When the solution is intended as a jointing substance for extremely good joints where only a flash of jointing compound is required on the surfaces with little or no beading at the edges of the joint, it has been found most convenient that it be prepared from 100 parts by weight of jelly and 100 parts by weight of carbon tetrachloride. Such a solution may be used in tropical climates.

EXAMPLEII When the solution is intended as a jointing substance for the average type of commercial joint where a fairly thick layer of jointing com pound is required on the surfaces, it has been found most convenient that it be prepared from 100 parts by weight of jelly and parts by weight of acetone. Such a mixture may be regarded as a general-all-round-purpose solution suitable for use in temperate climates.

EXAMPLE III When the solution is intended as a generalall-round-purpose jointing substance for application to the average type of commercial joint in tropical climates, it has been found most convenient that it be prepared from parts by weight of jelly and 40 parts by weight of carbon tetrachloride. Such a solution possesses approximately the sarne consistenc and drying rate in tropical climates as that of the abovementioned acetone-thinned solution in temperate climates.

When the above solutions are applied to a joint face, the thinners and toluene evaporate and leave the jointing medium.

The solution which is applied to the joint face and the vapours arising from it during drying thereon are non-inflammable when carbon tetrachloride is the thinner, since although toluene is inflammable, the quantity of carbon tetrachloride which is present in the solution is sufficient to render the mixture as a whole non-inflammable.

When acetone is employed as the thinner, the solution and the vapours arising from it are inflammable.

Although in the above description reference is made to the jelly obtained upon cooling the solution of the base in toluene, it is to be understood that there is no necessity for cooling this solution prior to the addition of thinner. Thus, the thinners may be added to the solution while it is hot and still in the liquid state.

From the foregoing it will be clear that a preferred jointing substance is obtained from a base prepared by heating sulphur with castor oil, the base being subsequently heated with toluene to form a jelly which is diluted with carbon tetrachloride or acetone to produce a substance readily capable of application to the joint faces by a brush.

Although in the description above reference is only made to castor oil it is to be understood that other fatty oils may be combined with sulphur to give similar rubber-like elastic compositions the properties of each of which depends to a considerable extent upon the oil which is used.

Solutions prepared by the above method were found to be satisfactory as joint sealing media, but the stronger solutions possessed a tendency to turn gelatinous during storage after a period which varied from 2-6 weeks, and in this condition they could not be applied so readily to the surfaces to be joined. This drawback was not noticed with the weak solution, i. e., that having 100 parts by weight of jelly in 100 parts by weight of carbon tetrachloride, samples of which were found to be quite stable at the end of four months storage. f

In anattempt to overcome the tendency of the stronger solutions to gel, and at the same time to find a more rapid method for dissolving the castor oil-sulphur product in toluene, it was found possible to add the cold toluene to the molten castor oil-sulphur product while the latter was at 226 C.- immediately the 2 to 5 minutes heating at this temperature was completed.

Since toluene boils at C. under normal atmospheric pressure, it was necessary to adopt a suitable technique in carrying out the process. This constitutes, in principle, the basis of the Example I Example II Example III Castor Oil-Sulphur base 150 150 150 Toluene 100 100 100 Carbon Tetrachlorida. 250 100 Acetone 37. 5

A suitable laboratory apparatus by which the cold toluene may be added to the molten castor oil-sulphur product is diagrammatically shown in Figure 2 of the accompanying drawing. Referring to this figure the apparatus is shown as comprising a flat-bottomed flask l the side wall of which is lagged with asbestos or other heat insulating material as at 8. Connected with the flask is a double-Wall condenser 9 and a funnel H], the latter being in communication with the flask by a pipe ll incorporating a tap l2. The funnel l and condenser 9 are connected together by a pipe I 3 and as is clear from Figure 2 the pipe i3 is a close fit into the upper part of the condenser 9 whilst the other end passes into and just below the neck of the funnel 10. The latter is open to atmosphere.

The assembly described rests upon a piece of wire-gauze [4 which covers a circular hole in the centre of an asbestos sheet I 5. The latter is suitably supported above a gas burner is and the arrangement is that the diameter of the hole in sheet I5 is slightly larger than the diameter of the fiat-bottom of the flask '5.

With the apparatus described the following procedure is adopted: the castor oil is introduced to the flask l (the condenser E and funnel I0 having previously been removed) and the gas burner I6 is lit so that the temperature of the oil is raised to 190 C. Thereafterthe sulphur is introduced and this causes the temperature to fall to about 170 C. Thereafter the mixture is heated slowly at the rate of approximately 2 C. per minute with constant gentle agitation until a temperature of 226 C. is reached. This tem peratureis then maintained for a duration of 3 to 5 minutes at the end of which time the con denser and funnel assembly is connected to the flask l and the toluene which has previously been introduced into the funnel i0 is run on to the hot mass within the flask l as quickly as possible by fully opening the tap H2. The tolume, immediately it reaches the molten mass within the flask, vaporizes rapidly and condenses in the condenser 9, but the small increase in pressure developed in the flask l as a consequence forces the condensate in the condenser through the pipe l3 and into the funnel 10 from whence it descends into the flask I. This cycle repeats itself ra idly until ultimately after about 30 seconds all the toluene from the funnel i0 is in the flask l whereupon the tap I2 is closed.

With the procedure described the castor oilsulphur product dissolves almost instantaneously in the toluene and it is believed that this is largely due to the small time interval during which the toluene is initially in contact with the hot mas in the flask 1 before vaporisation begins.

Having introduced the toluene to the flask as described the mixture is next boiled for a period of 30 minutes and then after being allowed to cool to approximately 50 C. the required amount of thinner is added to the mixture within the flask I from the funnel II]. It will be appreciated that this thinner has previously been introduced to the funnel l0 whilst the tap l2 remains closed. After the thinner has been introduced to the flask I the mixture is boiled fo a further period of 30 minutes and at the end of this time it is allowed to cool to room temperature whereupon it is transferred to suitable storage vessels which should be well sealed.

It is to be noted that the castor oil may b heated as quickly as possible to 190 0. prior to the introduction of sulphur but that once this additionhas been made it is important that the mixture be heated at a controlled rate. Heating from C. to 220 C. over a period of 20 to 25 'minutes has generally been found satisfactory.

If. the mixture be heated too quickly at this stage, there is a tendency for it to froth copiously with loss of sulphur the resulting compound then produced being found unsatisfactory. It is important for the same reason that the mixture be heated at 226 C. for not longer than 5 minutes.

It has been found that the rate of heating after the addition of sulphur, and. the duration of heating at 226 C. becomes of less importance when larger quantities of the compound are being prepared. The times quoted are to be understood therefore as applying to the specific apparatus shown in Figure 2 in which the flask 1' has a capacity of 3 litres and the funnel ID a capacity of 500 cos. I

The purpose of lagging the flask l as at B is to prevent the formation of a thin layer of undissolved castor oil-sulphur product which would otherwise solidify to the side of the flask during the addition of the toluene.

It will be appreciated, of course, that a plant based upon the principles of production described with reference to Figure 2 may be designed for industrial manufacture of the compound.

A jointing compound prepared as above described has been found to be effective for sealing leaks in petrol tanks, protecting rubber cables against fuel and oil, sticking rubber to glass and glass to metal. It is believed that compositions prepared in accordance with the present invention are capable of many other uses in addition to producing leak-proof joints without the use of packing materials.

I claim:

1. A process for the preparation of jointing composition, which process comprises adding sulphur to a fatty oil, the sulphur comprising between 10% and 43% by weight of the mixture, heating the mixture at a temperature between 220 C. and 240 C. maintaining the temperature for from 2 to 5 minutes to-produce a vulcanized base, dissolving or dispersing the base in a volatile, organic solvent chosen from the group consisting of toluene, xylene and solvent naphtha and dissolving the resultant mass in a chlorinated organic, aliphatic. solvent of the group consisting of trichlorethylene and carbon tetrachloride for thinning the same to the desired consistency for the jointing composition.

2. The process as claimed in claim 1, wherein chlorethylene.

3. The process as claimed in claim 1, wherein the chlorinated organic aliphatic solvent is carbon tetrachloride.

4. A process for the preparation of a jointing composition, which process comprises adding approximately 20 parts by weight of sulphur to 100 parts by weight of fatty oil, heating the mixture at a temperature in excess of 220 C. and raising the same to 226 C. maintaining said last mentioned temperature for from 2 to 5 minutes to produce a vulcanized base, dissolving or dispersing the base in a volatile, organic solvent chosen from the group consisting of toluene, xylene, and solvent naphtha and dissolving the resultant mass in a chlorinated organic, aliphatic solvent of the group consisting oftrichlorethylene and carbon tetrachloride for thinning the same to the desired consistency for the jointing composition.

5. A process for the preparation of a jointing composition, which process comprises heating 100 parts by weight of castor oil to 190 C., adding 20 parts by weight of flowers of sulphur thereto with continuous stirring, raising the temperature of the mixture to 226 C. over a period of 20 to 30 minutes, maintaining the mixture at 226 C. for 2 to 5 minutes to produce a vulcanized base, dissolving or dispersing the base thus formed in a volatile, organic solvent chosen from the group consisting of toluene, xylene and solvent naphtha and dissolving the resultant mass in a chlorinated organic, aliphatic solvent of the group consisting of trichlorethylene and carbon tetrachloride for thinning the same to the desired consistency for the jointing composition.

6. A process for the preparation of a jointing composition, which process comprises heating parts by weight of castor oil to C. adding 20 parts by weight of flowers of sulphur thereto with continuous stirring, raising the temperature of the mixture to 226 C. over a period of 20 to 30 minutes, maintaining the mixture at 226 C. for 2 to 5 minutes while agitating the same to produce a vulcanized base and allowing the vulcanized base to cool, adding 132 parts by weight of the base to 100 parts of an organic solvent chosen from the group consisting of toluene, xylene and solvent naphtha and boiling under reflux for 12 hours to form a jelly and upon subsequent cooling, diluting 100 parts by weight of'the jelly with between 15 to 100 parts by weight of a chlorinated organic, aliphatic solvent chosen from the group consisting of trichlorethylene and carbon tetrachloride for thinning the same to the desired consistency for the jointing composition.

ALAN THOMAS BARRINGTON. PARKHURST SQUIRES.

No references cited. 

1. A PROCESS FOR THE PREPARATION OF JOINTING COMPOSITION, WHICH PROCESS COMPRISES ADDING SULPHUR TO A FATTY OIL, THE SULPHUR COMPRISING BETWEEN 10% AND 43% BY WEIGHT OF THE MIXTURE, HEATING THE MIXTURE AT A TEMPERATURE BETWEEN 220*C. AND 240*. MAINTAINING THE TEMPERATURE FOR FROM 2 TO 5 MINUTES TO PRODUCE A VULCANIZED BASE, DISSOLVING OR DISPERSING THE BASE IN A VOLATILE ORGANIC SOLVENT CHOSEN FROM THE GROUP CONSISTING OF TOLUENE, XYLENE AND SOLVENT NAPHTHA AND DISSOLVING THE RESULTANT MASS IN A CHLORINATED ORGANIC, ALIPHATIC SOLVENT OF THE GROUP CONSISTING OF TRICHLORETHYLENE AND CARBON TETRACHLORIDE FOR THINNING THE SAME TO THE DESIRED CONSISTENCY FOR THE JOINTING COMPOSITION. 